5.2 Too small bounding boxes

The bounding box of a preview is determined by the LaTeX package
using the pure TeX bounding boxes. If there is material extending
outside of the TeX box, that material will be missing from the
preview image. This happens for the label-showing boxes from
the showkeys package. This particular problem can be
circumvented by using the showlabels option of the preview
package.

In general, you should try to fix the problem in the TeX code, like
avoiding drawing outside of the picture with PSTricks.

One possible remedy is to set
preview-fast-conversion to ‘Off’
(see The Emacs interface).
The conversion will take more time, but will then use the bounding boxes
from EPS files generated by Dvips.

Dvips generally does not miss things, but it does not understand
PostScript constructs like \resizebox or \rotate commands,
so will generate rather wrong boxes for those. Dvips can be helped with
the psfixbb package option to preview
(see The LaTeX style file),
which will tag the corners of the included TeX box. This will mostly
be convenient for pure PostScript stuff like that created by
PSTricks, which Dvips would otherwise reserve no space for.